Ink transfer media



Patented Apr. 7, 1936 UNITED .STATES PATT OFFlCE INK TRANSFER MEDIA PaulH. Gill, Belmont, Mass, as'signor to 'ihe Gill Corporation, Cambridge,Mass, a corporation of Delaware 4 Claims.

This invention relates to ink-transfer media comprising, broadlyspeaking, a flexible fibrous base and a pigmented oleaginous and/or waxyvehicle carried by the base, such as typified by typewriter ribbons andcarbon papers. Inasmuch as my invention may be applied with especialadvantage to such typewriter adjuncts as ribbons and carbon papers, Ishall confine the following description thereto, but it should beunderstood that my invention may be embodied in transfer mediaserviceable in connections other than with a typewriter.

In accordance with the present invention, I use as part of or as thecomplete oleaginous vehicle for the ink composition constituting theimpregnant of typewriter ribbons or the coating on carbon papers one ormore oils of an oxidizable character and I associate with such vehicle aphenolic compound that inhibits the, oxidation of such vehicle. Thismeans that a large number of oils that could heretofore be used onlywith disadvantage and hence generally used in limited amount, if at all,in making typewriter ribbons and carbon papers are rendered highlyvaluable for such purpose. Thus, it becomes possible in accordance withmy invention to use various animal or vegetable oils of an oxidizablecharacter, which are highly eifective as wetting or wettingout agentsfor the pigments suspended therein, in lieu of the mineral oilsheretofore used without running into the difficulties which wouldotherwise arise on account of the oxidizable character of such oils.Indeed, the presence of a suitable phenolic compound in such animal orvegetable oils as lard oil, neatsfoot oil, sesame oil, rapeseed oil, orthe like, which are by themselves unstable under atmospheric influences,inhibits the oxidation of such oil sufliciently so that the typewriterribbons are much longer lived and give much better satisfaction thanwould otherwise be the case, for, in the absence of the phenol, onewould run into one or more of such troubles as gum formation or glazingin the ribbons with attendant low recovery or tendency for the inkcomposition to difiuse into the spot last hit by the type, rancidity orfoul odor, and the development of undesirable stiffness or inflexibilityin the ribbons, all of which troubles would be accelerated by theexposure of the ribbons to sunlight and heat.

In applying the principles of the present invention in the making oftypewriter ribbons, I prepare an ink composition for impregnating theclosely woven high grade cotton, silk or other .fabric ordinarily usedas the flexible fibrous base or carrier'for the composition. The inkcompo- (Wll. 197-172) sition may, as usual, comprise finely groundlampblack or equivalent pigment, but rather than using mostly mineraloil as the oleaginous vehicle for such pigment, I prefer to use as mostor all of the oleaginous vehicle normally oxidizable oils 5 or blends ofoils of the character hereinbefore mentioned, e. g., lard oil. Such oilsare superior to mineral oils in their wetting or wetting-on propertiesof the pigments suspended therein and hence lead to typewriter ribbonsof improved ink- 10 transferring ability. Such oxidizable oils or blendsof oil are treated in accordance with my invention with about 0.5% to 2%or more of a suitable phenolic compound which is preferably soluble inthe oils. While it is possible to use 15 various phenols or phenoliccompounds as the inhibitors of oxidation or anti-oxidants of theoxidizable oils, I prefer to use an anti-oxidant selected from a groupconsisting of alpha naphthol, catechol, and pyrogallol, as these phenolshave 20 been found to be most-eifective as anti-oxidants of a largenumber of phenols examined as to antioxidative effect. Of the preferredthree phenols, I consider alpha naphthol to be best for the reason thatit is somewhat more effective as an in- 25 hibitor than catechol and farless expensive than either catechol and pyrogallol in terms of a giveninhibiting effect and does not have the color instability or acridity ofodor inhering in pyrogallol. Vaseline or equivalent body material may,if de- 30 sired, be added to the pigmented oleaginous vehicle containingthe anti-oxidant to impart thereto the desired consistency. If desired,a dye of the desired hue may also be added to the oleaginous vehicle.For instance, a black ink com- 35 position may not only be pigmentedwith lampblack, but be dyed with nigrosine or other suitable black dye.The resulting ink composition is squeezed into or otherwise introducedas an impregnant into the pores and interstices of the ribbon of fabricconstituting the base, the composition being heated, if desired, tofacilitate impregnation. The extraordinary effectiveness of alphanaphthol as an inhibitor of the oxidation of oxidizable oils can perhapsbest be appreciated from the fact that whereas some lard oils lacking aninhibitor become practically solid when kept for live days in an oven atF., the presence of about 0.5% to 2% of alpha naphthol therein preservesthem practically unchanged through the same treatment. The same appliesto red oil and to other oxidizable oils such as are used in accordancewith my invention.

In making carbon papers, ink composition of the same general characteras have been herein- 55 before described for use in making typewriterribbons are brought to the desired waxy consistency by the additionthereto of one or more such wax or waxlike bodies as carnauba wax,montan wax, ceresin, stearic acid, or the like, the consistency beingsuch that at low temperature the composition will not smooch clean paperlaid thereover, but at the same time will lend itself to transfer to thepaper under sensible pressure. The waxlike composition, whose oleaginousvehicle is stabilized in accordance with my invention, is applied in theusual manner as a coating oi the appropriate thickness upon a suitabletissue paper base, preferably a rag paper base. The anti-oxidant servesto impart the desired permanency to the resulting coated or carbonpaper, that is, to prevent the coating from becoming unduly hardened orembrittled and thereby acquiring a poor ink-transferring ability,becoming cracked or otherwise damaged and detracting unduly from thedesirable initial flexibility to the paper. I shall use the expression"pigmented oleaginous vehicle" to define generically the ink compositionserving as an impregnant in typewriter ribbons and/or the inkcomposition serving as a coating on carbon papers, even though suchlatter composition is of a waxy consistency, as it is the oleaginousvehicle that malres transfer of the inir composition possible in bothinstances. In saying that the oils used for the purposes of my inventionare of an oxidizable character, I mean that they contain one or moreunsaturated fatty acids or fatty acid giycerides in sufiicient amount torender such oils unstable or oxidizable in the presence or air, therebybecoming malodoroue or acquiring resinous or gummy oxidation prod note,or undergoing other physical and/or cheini- A cal changes.

I clainlz i. an inlr-transfer medium adapted for use with typinginstrumentalities comprising fibrous base, pigmented oleagincus vehiclecarried by such bare and being oi such highly onidiaabie character as tobe normally unsuitable for use in said medium, and an anti-oxidizingphenolic compound associated with said vehicle in amount adequate toinhibit the oxidation of said vehicle sumciently to render it suitablefor use in said medium in that said medium is capable of having a longuseful life while possessed of appropriate flexibility and diifusibilityof said vehicle irom one locality in said base to another.

2. An ink-transfer medium adapted for use with typing instrumentalitiescomprising a fibrous base, a pigmented oleaginous vehicle carried bysuch base and being of such highly oxidizable character as to benormally unsuitable for use in said medium, and alpha naphtholassociated with said vehicle in amount adequate to inhibit the oxidationof said vehicle suillciently to render it suitable for use insaid'medium in that said medium is capable of having a long useful lifewhile pomessed of appropriate flexibility and difiusibility of saidvehicle from one locality in said base to another.

3. An ink-transfer medium adapted for use with typing instrumentalitiescomprising a fibrous base, a pigmented lard oil carried by such base,and an anti-oxidizing phenolic compound associated with said 011 inamount adequate to inhibit its oxidation sufficiently to render itsuitable for use in said medium in that said medium is capable oi havinga long useful life while possessed of appropriate flexibility anddiffusibility of said oil from one locality in said base to another. v

d. An ink-transfer medium adapted for use with typing instrurnentalltiescomprising a fibrous base, pigmented lard oil carried by such base, andalpha naphthol associated with said oil in amount adequate to inhibitits oxidation sufllciently to render it suitable for use in said mediumin that said medium is capable oi having a long useful liie whilepossessed of appropriate flexibility and dliiusibility 01 said oil fromone locality in said base to another.

FAUL H.

